fix(remux): preserve encrypted HLS and test protocol restrictions

Allow nested crypto for encrypted HTTP HLS while rejecting top-level protocol wrappers and local-file access. Replace the HLS-only http_persistent option with HTTP multiple_requests across probe/remux/transcode paths, fixing the raw HTTP regression introduced by #124. Add real FFmpeg regression tests and PR CI.

.github/workflows/test.yml

@@ -0,0 +1,24 @@
+name: Regression Tests
+
+on:
+  pull_request:
+  push:
+    branches: [main]
+
+permissions:
+  contents: read
+
+jobs:
+  remux:
+    runs-on: ubuntu-latest
+    timeout-minutes: 10
+    steps:
+      - uses: actions/checkout@v7
+      - uses: actions/setup-node@v7
+        with:
+          node-version: 24
+          cache: npm
+      - name: Install FFmpeg
+        run: sudo apt-get update && sudo apt-get install -y ffmpeg
+      - run: npm ci
+      - run: npm test